Update actions/cache to v4.2.2 [full tests]

Github recently turned off their old caching APIs:
https://github.blog/changelog/2024-12-05-notice-of-upcoming-releases-and-breaking-changes-for-github-actions/#actions-cache-v1-v2-and-actions-toolkit-cache-package-closing-down

liboqs' CI started failing with the following error message for me:
This request has been automatically failed because it uses a deprecated version of `actions/cache: e12d46a63a90f2fae62d114769bbf2a179198b5c`. Please update your workflow to use v3/v4 of actions/cache to avoid interruptions.

This commit updates to the newer version of actions/cache that is using the
new Github APIs.

Note that Github's blog post is misleading. A lot more versions than v1/v2 are
being disabled including v3.3.3 that is used in liboqs - see
actions/cache#1510

Signed-off-by: Matthias J. Kannwischer <[email protected]>

.github/workflows/linux.yml

@@ -223,7 +223,7 @@ jobs:
         uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # pin@v4
       - name: Retrieve OpenSSL330 from cache
         id: cache-openssl330
-        uses: actions/cache@e12d46a63a90f2fae62d114769bbf2a179198b5c # pin@v3
+        uses: actions/cache@d4323d4df104b026a6aa633fdb11d772146be0bf # pin@v4
         with:
           path: .localopenssl330
           key: ${{ runner.os }}-openssl330
@@ -246,7 +246,7 @@ jobs:
       - name: Save OpenSSL
         id: cache-openssl-save
         if: steps.cache-openssl330.outputs.cache-hit != 'true'
-        uses: actions/cache/save@e12d46a63a90f2fae62d114769bbf2a179198b5c # pin@v3
+        uses: actions/cache/save@d4323d4df104b026a6aa633fdb11d772146be0bf # pin@v4
         with:
           path: |
             .localopenssl330